UC Irvine

Resonant photoelectron spectroscopy has been used to examine the electronic structure of Ce- and Yb-based heavy fermions. The experimental results are compared with Gunnarsson-Schönhammer calculations which include crystal field and finite Uff effects. Comparison of the model and experimental results reveals a large disparity between predictions and actual results. In particular, the Kondo model predictions of width, energy position and spectral weight for features near the Fermi level are not realized. Additionally, there is disparity between calculation and photoemission data in the Fermi-level crossing positions for spectral features very near the Fermi level. These discrepancies are present for both Ce and Yb heavy fermion systems. We see no evidence of spectral features in the photoemission data which can be uniquely identified with the Kondo resonance while our calculations show the resolution is adequate to clearly distinguish such features. © 1993.